Induction wireless communicating system



Oct. 25, 1966 TAKEO TAKEYA 3,281,591

INDUCTION WIRELESS COMMUNICATING SYSTEM Filed March 7, 1962 :5 Sheets-Sheet 1 IN V EN TOR. i' rA/nso TAKEYA' BYQ A/fomeya Oct. 25, 1966 TAKEO TAKEYA 3,231,591

INDUCTION WIRELESS COMMUNICATING SYSTEM Filed March '7. 1962 5 Sheets-Sheet 2 INVENTOR. TA K50 7% K5 YA Oct. 25, 1966 TAKEO TAKEYA 3,231,591

INDUCTION WIRELESS COMMUNICATING SYSTEM Filed March 7. 1962 5 Sheets-Sheet 5 INVENTOR. TAKEO TAKE. YA

United States Patent INDUCTION WIRELESS COMMUNICATING SYSTEM Takeo Takeya, 79 Jiyugaoka, Megnro-ku, Tokyo, Japan Filed Mar. 7, 1962, Ser. No. 178,077

Claims priority, application Japan, May 16, 1961,

36/ 16,845 8 Claims. (Cl. 2468) This invention relates to a communicating system utilizing a waveguide and more particularly to an induction wireless communicating system comprising a transmission line for microwaves formed by a transmission path formed by a waveguide and a plurality of radiating paths branched therefrom and suitable to be used in communications between a railway car such as a train, electric car, or other vehicle travelling along a particular path and a supervisory oflice or between running vehicles.

As means for communicating intelligence between such vehicles as trains and the supervisory ofiice, or between trains, so-called wireless communicating systems have been widely used wherein electric waves are propagated through the air. In such systems, however, broad band communication, as well as multiplex communication, is difiicult because propagation in the air of electric waves is greatly affected by bodies, such as earth configurations and buildings, as well as by the weather and the like. The quality of communication is also impaired by space noise and because the frequency band of the electric wave used or its frequency band width is limited. In recent years induction wireless communicating systems have been developed capable of eiTecting multiplex communication without being afiected by such external conditions as earth configuration, weather and the like, and which are less susceptible to noise in received signals. In these systems microwave'transmitting and receiving devices and associated antenna are mounted on trains and like vehicles, a fixed wireless station provided with microwave transmitting and receiving devices is situated at the supervisory office, and a waveguide connected with the fixed wireless station is extended in parallel with the rail or track for the trains and the like. A plurality of slits are provided at a predetermined spacing on the side of said waveguide facing the train and, similarly, a plurality of slits are provided at a predetermined spacing on the antenna mounted on the train to oppose said slits of the waveguide. With such an arrangement, when an intelligence electric wave is sent out from the fixed wireless station by microwave, after propagating through the waveguide serving as the transmission line, the intelligence electric wave is radiated in the surrounding air through said slits. Antennas mounted on trains catch this radiated wave to introduce it into the associated receiving devices to receive the intelligence. In order to transmit intelligence in the reverse direction, that is, from trains to the fixed wireless office, transmitting devices on trains are operated to radiate the intelligence wave from the antenna. The radiated wave will enter into the waveguide through its slits and propagate through it toward the receiving device at the fixed wireless station. In like way, communication of intelligence between trains are effected through said waveguide having slits. In this proposed system, however, it is required to maintain a particular relation between the length of antenna and the spacing between adjacent slits. This comes about because, unless the length of the antenna is made longer than the spacing between slits of the waveguide serving as the transmission line, radiated waves from the waveguide and received by the antenna on the train, as well as electric waves radiated by the antenna and introduced into the waveguide would be intermittent. Moreover, in order to transmit the electric wave over long distances attenuation of the wave must be minimized as far as possible and to attain this object, the length of spacing between adjacent slits of the waveguide should be somewhat longer.

Large spacing between slits suitable for long distance transmission results in considerable increase in the length of the antenna which is required to be larger than said spacing by the reason above pointed out. No train, however, can run without any tilting but rolls with reference to its direction of advance so that the distance between antenna and two adjacent slits .of the waveguide facing the antenna will vary substantially. It is clear that this phase difference will be increased as the length of the antenna is increased. Due to the phase difference in said space distances produced by this reason the length of the wave propagating paths between two adjacent slits and the receiving device on the train or the receiving device in the fixed wireless station will become different, so that radiated waves respectively radiated through adjacent slits and received by the antenna will enter into the receiving device with an appreciable phase difference. Also the intelligence Wave from the train will be received by the fixed wireless station with phase difference, thus resulting in reduction of the receiving gain and in instability. While these drawbacks can be eliminated by decreasing the length of the spacing between slits, such means can not be used because decrease in the length of slit spacing results in an increase of attenuation of the wave propagated.

Accordingly, the principal object of this invention is to eliminate above mentioned difficulties.

In accordance with this invention there is provided an induction wireless communication system suitable to communioate intelligences between a fixed wireless station and vehicles equipped with microwave transmitting and receiving devices and an associated antenna and between said vehicles wherein a waveguide serving as the transmission path for microwave is laid along and in parallel with a rail or track and a radiation path is inductively coupled to said waveguide to one end of which is connected said fixed wireless station.

It is an object of the present invention to provide a novel induction wireless communicating system wherein a transmission line is formed by a transmission path comprising a waveguide laid parallel to a rail or track and a radiating path which is electrically coupled with said transmission path to radiate or receive microwaves, a fixed wireless station provided with microwave transmitting and receiving devices is situated at one end of said transmission path and vehicles running along said rail or track are equipped with microwave transmitting and receiving devices and their associated antenna, so that waveguide serves only to propagate the microwave and radiation and reception of the microwave are effected by said radiating path instead of said waveguide thereby compromising the requirement that attenuation of the wave energy should be minimum and the requirement to improve the radiation pattern. Moreover, according to this invention since it is able to make the antenna sufficiently short, even when the vehicle rolls, phase difference in the wave caused by an unbalanced condition between the transmission line and the vehicle is greatly reduced, thus decreasing attenuation of the propagating energy and preventing decrease in the gain of the received signal. Thus, the present system can eltect accurate and stable exchange of intelligences over a long distance. More particularly, in a conventional system wherein the waveguide is used for both transmission and radiation of the wave, for uniform distribution of radiated wave throughout the whole transmission line, it is necessary to make the length of the spacing between slits of the J9 waveguide extremely small so that, in case of a long distance transmission, the wave energy at the terminal is greatly attenuated which makes diflicult not only long distance transmission but also uniform distribution of the energy of the radiated wave.

On the contrary, in the system embodying the present invention, since slits may be provided for the waveguide at substantial spacings and, since the wave is radiated by a radiating path which is electrically coupled 'with said waveguide through said slits, it is only required to assure uniform distribution of the energy of the radiated wave along the transmission line without considering the attenuation accompanied by the transmission of the wave through the radiating path. Furthermore, in accordance with the present invention, by changing the size or number of said slits in the waveguide the degree of directional coupling between the respective radiating paths and the waveguide can be adjusted whereby it is possible to make the powers of waves radiated from the respective radiating paths uniform.

It is a further object of the present invention to adjust the phase diiference of the respective radiating paths caused by various factors by providing a phase adjuster for the radiating path constituting the transmission path.

Still another object of the present invention is to provide a novel radiating path which is coupled electrically with a waveguide serving as a transmission path wherein the radiating path is formed not only by the waveguide but also by a G line or a dielectric deposited on the outer surface of the waveguide acting as the transmission path, thus improving radiation pattern and reducing its size to save space and cost of installation.

The present invention also contemplates the provision of a new and improved induction wireless communicating system wherein the transmission line is laid between two rails or tracks or in a single rail or track hereby permitting a single transmission line to be used for intelligence communication for double tracks and eliminating the necessity of utilizing a site outside the railroad or track for laying the transmission line.

The features of the invention which are believed to be novel are set forth with particularity in the appended claims. The invention itself, however, as to its organization together with further objects and advantages thereof, may best be understood by reference to the accompanying description taken in connection with the accompanying drawings, in which FIG. 1 shows schematically principal portions of a conventional induction wireless communicating system;

FIG. 2a is a side elevation of a transmission line embodying this invention;

FIG. 2b is a plan view of the transmission line shown in FIG. 2a;

FIG. 3 is an enlarged side view of a portion of the transmission line shown in FIG. 2a;

FIG. 4 is a side elevation of a modification wherein a directional coupling device is utilized instead of the main slit in FIG. 3;

FIG. 5a is a side elevation illustrating another embodiment of this invention modified from the transmission line shown in FIG. 2;

FIG. 5b is a plan view of the transmission line shown in FIG. 5a;

FIG. 6 is a side view of another transmission line different from the embodiment shown in FIG. 5;

FIG. 7 is a side view of a transmission line illustrating still another modification; and

FIG. 8 shows a portion of the transmission line to illustrate one example of a phase adjuster provided in the radiating path of the transmission line.

Referring now to the accompanying drawings, as shown by the plan view of FIG. 1, a transmission line of a conventional communicating system comprises a waveguide a which is connected at one end thereof with a fixed wireless station, not shown, and is laid along one side of and in parallel with rails C on which a .train 11 travels. Through the side wall of the waveguide a facing the train b there are provided a number of slits e, e e with a fixed spacing d therebetween.

An antenna fis mounted on the side of the train b facing the waveguide a and connected with microwave transmitting and receiving devices g disposed in the cab. By the prior transmission line having the construction shown in FIGURE 1 and hereinabove described, a single waveguide is utilized to transmit the microwave and the microwave is directly radiated through the slits of the waveguide. In accordance with the present invention, however, it is contemplated to exchange .intelligences or to send command intelligences through a novel transmission line to be explained more in detail with reference to FIG. 2a to FIG. 6. While not shown in the drawing, the rails are to be situated in front of and behind the transmission line 1 in FIG. 2a and in the upper and lower sides in FIG. 2b. Stated in another way, the transmission line 1 is laid between two rails in parallel therewith. Furthermore, although not shown in the drawing it is understood that the vehicle, such as a train, is to be equipped with an antenna and associated microwave transmitting and receiving devices as in the prior system. The transmission line 1 shown in FIGS. 2a and 2b comprise a transmission path 2 in the form of a waveguide with one end connected with a fixed wireless station (not shown) and plurality of radiating paths 3, 3 3 formed by a plurality of waveguides each electrically coupled to said transmission path 2. The waveguide serving as the transmission path 2 is formed by a hollow cylindrical waveguide in order to transmit wireless wave energy with low power loss over a long distance. Directly above the longitudinal axis of the waveguide, there are provided a plurality of main slits 4, 4 4 with a definite interval or spacing determined by considering the factor that attenuation of the wave may not exceed -a certain amount for practical use in the case of a long distance wave transmission. Each of the radiating paths 3, 3 3 comprises a hollow coupling portion 5, 5 5

. respectively projecting radially outward from said transmission path 2 having bottom ends connected thereto to surround one of the main slits 4, 4 4 respectively, and bent substantially at right angles from said coupling portion to extend substantially in parallel with the longitudinal axis of the transmission line 2.

The free ends of the radiating portions 7, 7 7 are terminated in closed ends 6, 6 6 respectively, and on the both side surfaces of each of the radiating portions facing the rails are provided a plurality of auxiliary or sub-slits 8, '8 8 adapted to radiate or receive microwaves. Thus, the radiating paths 3, 3 3 extend directly above the longitudinal axis of the transmission line 2. It is preferable to form these radiating paths by waveguides with rectangular or square cross-section to facilitate radiation and reception of the wave. As best shown in FIG. 2a, it is advantageous to superpose the end portion of the respective radiating portions 7, 7 7

upon the coupling portions 5, 5;, 5 of the next succeeding radiating portion to make the assembly rigid. When assembling radiating paths 3, 3 3 in this manner, care should be taken to align the final sub-slit 8,,, which is nearest the end of one radiating portion 7 with the first sub-slit 8 of the next succeeding radiating portion 7 which is nearest its coupling portion 5 as shown in FIG. 3 while at the same time, matching the combined electric field characteristics of both slits S and 8 with the respective electric field characteristics of the remaining sub-slits 8 8 8,, provided with definite spacing D in order to improve the radiation pattern. Instead of overlapping the ends of the successive radiating portions as illustrated in FIGS. 2a, 2b, and 3, the ends 6, 6 6 of the radiating portions 7, 7 7 may be terminated in contact with or short of the side surfaces of the coupling portions 5, 5 5

so to extend radiating portions 7, 7 7 2 in parallel with the transmission path. In such a case, for the same reason as above stated, it is necessary to make equal the distance between the final sub-slit of one path and the first subslit of the next succeeding radiating path and the spacing D between remaining slits or to make said distance equal to an integral multiple of M2 where A is the wave length.

The intelligence wave emitted from the fixed wireless station propagates through the transmission path. Since the spacings D between adjacent main slits 4 and 4 and 4 and 4 are selected to be sufficiently wide enough to minimize the attenuation of the electric wave, the intelligence wave will have sufiicient magnitude for practical purposes even at the last main slit 4,, (not shown). This propagated wave will be introduced into the respective radiating paths 3, 3 and 3 to radiate through subslits 8, '8 8 provided in the wall of the radiating portions 7, 7 7 with small spacings D. However, since the length of the radiating portion 7, 7 7 is short, the electric field characteristic of the sub-slits 8,

8 8 is nearly uniform, and since the spacings D between the sub-slits are very small with respect to said spacings D the radiation pattern created by said radiating paths 3, 3 3 is improved. In other words, according to this invention the transmission path 1 is constituted by the transmission path 2 which principally serves to transmit wireless wave energy and radiating paths 3, 3 3 which are utilized exclusively to radiate or receive the wireless wave, so that it is possible to make the spacings D between main slits 4, 4 4 of the transmission path 2 relatively large and hence to make the attenuation of the wave energy small. Moreover, the radiating paths 3, 3 3 can be designed to improve radiating condition without regard to said transmission path 2. Thus inasmuch as the spacings D between subslits 8, 8 8 of the radiating portions 7, 7 7 can be made to be sufficiently sm-all without any accompanying appreciable attenuation of the electric wave in the transmission path 2, antennas to be mounted on vehicles such as trains can also be made sufficiently small whereby there is no fear that the intelligence wave may reach with phase difference to the microwave receiving device mounted on trains and like vehicles even when they roll.

Although in the embodiment shown in FIG. 3 main slits are utilized to couple electrically the transmission path and the radiating path, in the modification shown in FIG. 4, a wide band coupling device or more generally a directional coupling means DCP comprising a plurality of slits 4 4 and 4 in the wall of the transmitting path 2 is used (these slits may be in the form of circular openings). Directly above these slits extends a horizontal coupling portion 5 communicated with the coupling portion 5 and a terminal resistor 4 is disposed within the terminal portion 5 projecting from said horizontal coupling portion 5 substantially in parallel with the coupling portion 5 These terminal resistor 4 and the plurality of slits 4 4 4 provides a function corresponding to that of a single main slit in FIG. 3.

Theoretically, the phases of waves propagated through the respective radiating paths are the same, and small difference in the phases which may be present in the actual construction can be adjusted by phase adjusters P, P P included in the respective coupling portions 5, 5 5 of the radiating paths. As illustrated in FIG. 8 these phase adjusters P may take a form wherein the length of the coupling portions 5, 5 5 connected around slits 4, 4 4 of the transmission path 2 can be varied by sliding coupling waveguides 9 in the directions A and A. It should be understood that instead of inserting the phase adjuster P in the coupling portion 5, it can be inserted in any appropriate portion of the radiating portions 7, 7 7 and that any other equivalent phase shifting means may be used, such as, for example,

varying the width of the waveguides comprising the radiating paths 3, 3 3

Resistors R, R R inserted in the ends 6, 6 6 of respective radiating paths are provided for the purpose of eliminating undesired standing waves in these radiating paths thereby producing a desired electric field characteristic from sub-slits 8, 8 8 While it is not always necessary to make equal phase speeds of the transmitting path 2 and of the radiating paths 3, 3 3 it is advantageous to make them substantially equal in order to improve the frequency chracteristic, and to eliminate the discontinuity or turbulence of the radiated microwave energy caused by the resultant of the two microwave radiated energies having the different phases or especially phases at the point between the end of one radiating waveguide and the beginning of adjacent radiating waveguide. These two microwave energies are radiated from the end portion of one radiating waveguide and the beginning portion of adjacent radiating waveguide.

The transmission line 1 of the embodiment shown in FIGS. 5aand 5b is similar to that shown in FIGS. 2a and 211 except that on one side of the transmission path 2 there are formed radiating paths 3, 3 3 constituted by waveguides and that sub-slits 8, 8 8 are perforated through the side wall of the radiating portions of said radiating paths facing the vehicle, so that their components are identical and corresponding parts are shown by the same reference numerals. The transmission line 1 shown in FIGS. 5a and 5b can not be used for vehicles running on double tracks but is suitable for a single track, but instead of providing sub-slits 8, 8 8 in the side surface, as shown in FIG. 5a by perforating these sub-slits through the upper surface of the radiating paths and by laying them between rails or within a track to cooperate with an antenna mounted beneath the bottom of vehicles it becomes possible to communicate intelligences without utilizing a wide site for installing the transmission line 1.

Although in the embodiments shown in FIGS. 2a, 2b, 5a and 5b, rectangular waveguides are utilized as the radiating paths 3, 3 3 it should be understood that any other suitable waveguides can be used provided that it can provide uniform distribution of the electric field along the transmission line 1. For example, in the em bodiment shown in FIG. 6, G lines are utilized as the radiating paths 3, 3 3 The base ends of the G lines are respectively coupled electrically with the respective coupling portions 5, 5 5 similarly projected from the transmission path 2 at a definite spacing D, and the free end of each G line is extended to overlap the coupling portion of the next succeeding G line to assure uniform distribution of the electric field radiated from each G line. In the modification illustrated in FIG. 7 in lieu of utilizing G lines, radiating paths 3, 3 3 formed by a waveguide with a coating of a dielectric applied on its outer surface to act as a transmission path 2, said dielectric being fed with electric energy through coupling portions 5, 5 5 Numerals 10, 10 10 represent gaps in the dielectric. It will be understood that these transmission paths formed by G lines or a dielectric can be laid between adjacent rails of a set of double tracks to cooperate with vehicles running on both tracks, just in the same manner as has been described in connection with the embodiments of FIGS. 2a, 2b, 5a and 5b.

While the invention has been explained by describing particular embodiments thereof, it will be apparent that improvements and modifications may be made without departing from the scope of this invention as defined in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An induction communication system comprising a transmission line laid substantially parallel to a rail or track, said transmission line comprising a transmission path comprising a cylindrical waveguide having a plurality of main slits perforated through its wall at substan- 7. tially equal spacing from each other, a coupling portion pertaining to each main slit including a second waveguide extending substantially at a right angle to said transmission path, said coupling portion comprising a base portion secured to said cylindrical waveguide around the respective said main slit, each coupling portion also comprising a radiating portion formed by a third Waveguide parallel to said cylindrical waveguide, said third Waveguide being connected with said coupling portion, and a plurality of substantially equally spaced sub-slits in each said third waveguide being designed to have equal phase speeds to obtain a constant radiating field along the track or rail by eliminating the discontinuity or turbulence of radiated microwave energy.

2. An induction wireless communicating system comprising a transmission line having a common waveguide to radiate microwave, a plurality of radiating paths spacedly arranged along and close to said waveguide and coupling means for effecting electrical. loose coupling of each of said radiating paths and said waveguide, an antenna mounted on a vehicle travelling along rails or tracks positioned in parallel with said transmission line, microwave transmitting and receiving devices connected to said antenna, thereby to communicate intelligences by microwave between said transmission line and said transmitting and receiving devices, said transmission line comprising a a transmission path formed by a cylindrical waveguide having a plurality of main slits perforated through its wall at substantially equal spacing, coupling portions of each formed by a second waveguide with its base end fixed around said main slit and projecting substantially at right angles from said transmission path and a radiating portion formed by a third waveguide which is electrically connected to said coupling portion to extend in parallel with said transmission path, said third waveguide having a plurality of sub-slits perforated through its wall at substantially equal spacing, the end of one radiating portion being positioned in contact with or close to the side surface of an adjacent radiating portion, and th spacing between the last sub-slit closest to the end of one radiating portion and the first sub-slit of the next succeeding radiating portion being selected to be equal to the spacing between remaining sub-slits which is an integral multiple of M2, Where is the wave length.

3. An induction wireless communicating system comprising a transmission line having a common waveguide to radiate microwave, a plurality of radiating paths spacedly arranged along and close to said waveguide and coupling means for effecting electrical loose coupling of each of said radiating paths and said waveguide, an antenna mounted on a vehicle travelling along rails or tracks positioned in parallel with said transmission line, and microwave transmitting and receiving devices connected to said antenna, thereby to communicate intelligences by micro- Wave between said transmission line and said transmitting and receiving devices, said transmission line comprising a transmission path formed by a cylindrical waveguide, and a radiating portion formed by a second waveguide which is coupled with said transmission path through a directional coupling device and having sub-slits perforated through its wall, one end of said second waveguide being positioned in contact with or close to the adjacent radiating portion, and the spacing between the last sub-slit closest to the end of one radiating portion and the first sub-slit of the next succeeding radiating portion being selected to be equal to the spacing between remaining sub-slits which is an integral multiple of M2 where is the wave length.

4, An induction wireless communicating system comprising a transmission line having a common waveguide to radiate microwave, a plurality of radiating paths spacedly arranged along and close to said waveguide and coupling means for effecting electrical loose coupling of each of said radiating paths and said waveguide, an antenna mounted on a vehicle travelling along rail-s or tracks positioned in parallel with said transmission line, and microwave transmitting and receiving devices connected to said antenna, thereby to communicate intelligences by microwave between said transmission line and said transmitting and receiving devices, said transmission line comprising a transmission path formed by a cylindrical Waveguide with main slits perforated through its wall at substantially equal spacing, coupling portions each formed by a second waveguide having a base end secured around one of said main slits and projecting substantially at right angle from said transmission path and a plurality of radiating portions each formed by a third waveguide which is parallel to the transmission path and connected with one of said coupling portions and having a plurality of subslits perforated through its wall at substantially uniform spacing, one end of one radiating portion being positioned to overlap the coupling portion of the adjacent radiating portion, said main slits and sub-slits being perforated such that the last sub-slit closest to the end of one radiating portion substantially aligns with the first sub-slit of adjacent radiating portion and that the resultant electric field characteristic produced by said last and first sub-slits is identical with those produced by other sub-slits.

5. An induction wireless communicating system comprising a transmission line having a common waveguide to radiate microwave, a plurality of radiating paths spacedly arranged along and close to said Waveguide. and coupling means for effecting electrical loose coupling of each of said radiating paths and said waveguide, an antenna mounted on a vehicle travelling along rails or tracks positioned in parallel with said transmission line, and microwave transmitting and receiving devices connected to said antenna, thereby to communicate intelligences by microwave between said transmission line and said transmitting and receiving devices, said transmission line comprising a transmission path formed by a cylindrical waveguide, and radiating portions each formed by a second Waveguide which is electrically coupled with said transmission pat-h through a directional coupler and parallel thereto and having sub-slits perforated through its wall, one end of one radiating portion being positioned to over lap the adjacent radiating portion and said sub-slits being perforated in such a manner that the last sub-slit closest to the end of one radiating portion substantially aligns with the first sub-slit of the succeeding radiating portion and that the resultant electric field produced by said last and first sub-slits is identical with those produced by other sub-slits.

6. An induction Wireless communicating system comprising a transmission line laid in substantially parallel relation with respect to rails or a track, said transmission line being formed by a transmission path in the first form of a first waveguide and a radiating path in the form of further waveguide means connected to said waveguide and having a phase adjuster and adapted to radiate and receive a microwave, said transmission path and said radiating path having equal phase speeds to obtain a constant radiating field along the track or rail by eliminating the discontinuity or turbulence of radiated microwave energy, a fixed wireless station situated at one end of said transmission path and having microwave transmitting and receiving devices, and microwave transmitting and receiving devices and associated antenna equipped on a vehicle travelling along said rail or track whereby to communicate intelligences between said fixed wireless station and said vehicle or between vehicles through said transmission line including said transmission path and said radiating path.

7. An induction wireless communicating system comprising a transmission line laid in substantially parallel relation with respect to rails or a track, said transmission line being formed by a transmission path in the form of a waveguide and a radiating path electrically coupled with said transmission path and parallel therewith and adapted to radiate and receive microwaves, said transmission path and said radiating path having equal phase speeds to obtain a constant radiating field along the track or rail by eliminating the discontinuity or turbulence of radiated microwave energy, a fixed wireless station situated at one end of said transmission path and including microwave transmitting and receiving devices, microwave transmitting and receiving devices and an antenna associated therewith, both equipped on each vehicle travelling along said rails or track whereby to communicate intelligences by means of microwaves between said fixed wireless station and said vehicle or between vehicles through said transmission line including said transmission path and said radiating path.

8. An induction wireless communicating system comprising a transmission line laid substantially in parallel relation with respect to rails or track or between rails or within a track, said transmission line including a transmission path in the form of 'a waveguide and a radiating path electrically coupled with said transmission path and substantially parallel therewith and adapted to radiate and receive microwaves, said transmission path and said radiating path having equal phase speeds to obtain a constant radiating field along the track or rail by eliminating the discontinuity or turbulence of radiated microwave energy, a fixed wireless station having microwave transmitting and receiving devices and situated at one end of said transmission path and microwave transmitting and receiving devices and an associated antenna equipped on a vehicle travelling along said rails or track, whereby to communicate intelligences by microwave between said fixed wireless station and said vehicles or between vehicles through said transmission line including said transmission path and said transmission path.

References Cited by the Examiner UNITED STATES PATENTS 2,580,155 12/1951 Brannen 24630 X 2,618,744 11/1952 Braden 325-24 2,624,003 12/1952 Iams 343--771 X 2,636,113 4/1953 Deloraine 2468 2,641,688 6/1953 Adams 2468 2,702,342 2/1955 Korman 246--30 2,765,401 10/ 1956 Riblet 32524 2,961,658 11/1960 Spencer et al 343771 X 2,993,205 7/1961 Cooper 343771 3,032,762 5/1962 Kerr 343-771 3,078,463 2/1963 Lamy 343771 FOREIGN PATENTS 159,236 10/ 1954 Australia.

ARTHUR L; LA POINT, Primary Examiner.

LEO QUACKENBUSH, EUGENE G. BOTZ, Examiners.

S. B. GREEN, Assistant Examiner. 

1. AN INDUCTION COMMUNICATION SYSTEM COMPRISING A TRANSMISSION LINE LAID SUBSTANTIALLY PARALLEL TO A RAIL OR TRACK, SAID TRANSMISSION LINE COMPRISING A TRANSMISSION PATH COMPRISING A CYLINDRICAL WAVEGUIDE HAVING A PLURALITY OF MAIN SLITS PERFORATED THROUGH ITS WALL AT SUBSTANTIALLY EQUAL SPACING FROM EACH OTHER, A COUPLING PORTION PERTAINING TO EACH MAIN SLIT INCLUDING A SECOND WAVEGUIDE EXTENDING SUBSTANTIALLY AT A RIGHT ANGLE TO SAID TRANSMISSION PATH, SAID COUPLING PORTION COMPRISING A BASE PORTION SECURED TO SAID CYLINDER WAVEGUIDE AROUND THE RESPECTIVE SAID MAIN SLIT, EACH COUPLING PORTION ALOS COMPRISING A RADIATING PORTION FORMED BY A THIRD WAVEGUIDE PARALLEL TO SAID CYLINDRICAL WAVEGUIDE, SAID THIRD WAVEGUIDE BEING CONNECTED WITH SAID COUPLING PORTION, AND A PLURALITY OF SUBSTANTIALLY EQUALLY SPACED SUB-SLITS IN EACH SAID THIRD WAVEGUIDE BEING DESIGNED TO HAVE EQUAL PHASE SPEEDS TO OBTAIN A CONSTANT RADIATING FIELD ALONG THE TRACK OR RAIL BY ELIMINATING DISCONTINUITY OR TURBULENCE OF RADIATED MICROWAVE ENERGY. 